Sizes 8-10" and 10-12" are 7/8" wide and taper down to 5/8" at the buckle

Sizes 12-14" and 14-16" are 1" wide and taper down to 5/8" at the buckle

Sizes 16-18", 18-20", 20-22" and 22-24" are 1 1/4" wide and taper down to 7/8" at the buckle.

These collars are measured from the end of the buckle to the first hole and to the last hole. The adjustment from the first hole to the last is 2 inches. There are five holes. To measure for your dog, use a cloth tape measure or a piece of string and measure snugly, but not tightly around your dog's neck. This will be the small length of the collar. This leaves up to 2 inches to lengthen the collar to make it fit comfortably.